Mechanical relay of the fluid jet type



Oct. 1, 1946. R. c. BRAIT HWAITE ETAL 2,408,603

MECHANICAL RELAY OF THE FLUID JET TYFE Filed Oct. 9, 19,45

' NY N B ATTORNEYS Patented Oct. 1, 1946 UNITED STATE MECHANICAL RELAYVOF Timrwm JET TYPE Robert Cecil Braithwaite and Kenneth Wilcox- Manchester, England, assignorsto Metropoli- 'tan-Vickers Electrical Company Limited, Lon'- don, England, a company of Great Britain Application ctober 9, 1943, Serial No. 505,708. In Great Britain May 28, 1940 This invention relates to mechanical relays of thefluid jet type and has for its, object to reduce the reaction imposed upon the controlling member of the relay. v V, r y

A relay of the type referred to comprises'a nozzle to; which air or otherfluid is" continuously supplied; usually at constant pressure, and anothernozzle' or other orifice which receivesffluid from the jet; issuing from Ithe'l aforementioned nozzle, The. nozzle and orifice'i'areusually en sometimes provided with means whereby'the 'pressurejwithin the casing may be controlled.

. In certain applications "of mechanical relays, and particularly fluid jet type.re1ays it is'arequirement that the controlling'force or torque for initiating frelay' actions'hall be a minimum for, in other words, that vthe'reshall be the least possible reaction 'f'romthe fluid jet issuing from ithejsupply" nozzle uponthe controlling device or the measuring device in order to minimize disturbance of the force'which effects'co'ntrol. For

nozzle which is supplied with fluid whereby the jet of fluid'impingeslto 'ag'reatenor less extent upon the stationary receivingorifice, or in another arrangement the nozzle and receiving oriflce are relatively fixed and the control is effected by means of a vane or baflle which is variably interposed in the fluid jet. The fluid variably received by the receiving orifice may actuate for example, a piston 'or bellows member which in turn may efiect control of some other apparatus.

It has been discovered that in the case of the movable jet type of relay the aforesaid reaction is still too high for certain uses of the relay and this has been found to be due to the fact that the jet of fluid tends to bring the jet back into alignment with the receiving orifice. Also when using a vane or baiile type of control it has not been found possible sufl'iciently to reduce the reaction by designing the shape or nature of the vane or baiile to remove the reaction whilst obtaining reliable results. It has been found in practice that in either of said types of relays, and more particu; larly in the type employing a. tilting nozzle from which the jet issues, a false and undesirable load is imposed on the delicate instrument tilting such nozzle, or moving the vane interposed in the fluid jet, due it is believed, to rebounding oi the fluid 4Claims. (01.137-111) from the end face of the receiving nozzle, and

closed in, a i'c'asing hav ng outletjport jan'd possibly also to eddy currents, the tendency of which influence is to re-centralize the nozzle from which the jet issues. These defects have been alleviated by the present invention in which the control is efiected by varying the quantity of fluid which enters the receiving nozzle by means which, for certain particularly delicate types of mechanism, ismostfconveniently in the form of a third or controlling nozzle mounted in a novel manner which avoids disturbing or objectionable reaction thereon;

"According to the present invention the reaction of the, fluid jet issuing from the supply nozzle upon the controlling memberis reduced to a very smallvalue without loss of controllingaccu-' racy by deflecting said jet from alignment with v the receiving orifice by means of another jet which is supplied from a movably mounted defleeting or controlling-nozzle so as variably to impinge upon the main jet of fluid issuing from the supply nozzle. -Reaction from the fluid jet issuing from the supply nozzle upon the jet from the deflecting or controlling nozzle 'is minimized by mounting the deflecting nozzle to move about an axis which is so disposed with respect to the direction of efliux from the supply nozzle that this eillux produces no torque of the deflecting nozzle aboutitsaxisof movement.

'the supply and receiving nozzles by the deflecting A graduated control of-t he'main jet between jet may be attained either by shaping the deflecting or controlling nozzle so that it gives a fantail flow for which purpose this nozzle may have a flattened or slit-like orifice, or by using two jets impinging upon one another in the manner used in certain forms of acetylene gas burners for illumination.

In certain applications of a relay embodying the invention it may occur that the necessity for having the minimum reaction on the measuring device only arises over a certain range of movement of that device, for instance very near to its normal zero position, while major deflections may occur under initial starting or abnormal conditions, when much greater reaction is relatively unimportant. According to a feature of the invention, therefore, the control nozzle may also carry a vane or bafile which normally does not come within the field of the main jet but with large deflections is brought into action and then assumes control of the main jet.

In carrying out the invention the direction of axis of the controlling nozzle may be at right angles to the axis or the main Jet and movable of the servo device initiated by movement of'the controlling nozzle about its axis may be made either to tend to restore the position otthis nozzle towards its previous position or to move the Q remainder of the apparatus carrying" the mainnozzle and receiving orifice to follow' up" the movement of the controlling nozzle. l

The invention will now be" described with ref:

4 the fixed nozzle I to the fixed nozzle 2. At II is represented in dotted lines the fan-tail jet obtained by flattening the nozzle 4 as at 4* in Fig. 2, and at I2 is shown the added vane, which may be soldered to the movable nozzle 4 and which is particularized by the shaped edge I2 such that when the nozzle is deflected considerably in the direction of the arrow, the main jet I will be slicd,- Soto speak, to a varying amount by the vane I2.

Figure 4 shows another arrangement employmg ano zie' 4* similar to that of an acetylene gas Burner and which produces two jets I3 and I4 erence to the accompanying drawing, whichis somewhat diagrammatic and in which:

Figure 1 is a perspective View of a fluid jet relay in accordance with the invention.

Figure 2 is a similar View of the three jets showing the formation thereof.

Figure 3 is a diagrammatic view snewinethe controlling nozzle in elevation and provided with a vane orbafiie for controlling the main jet.

Figure 4 is a diagrammatic view of a two-jet nozzle for controlling the main jet. I

In the drawing l is the nozzle to which the fluid is continuously supplied under constant pressure, whilst 2 is the receiving nozzle or. orifice, these members I and 2 being mounted on a base member or carrier 3. At 4 is shown the third nozzle which in the example illustrated provides a jet at right angles to the fluid jet passing between the nozzle I and orifice 2. The nozzle 4 is mounted on a member S carried in a bracket 6 and rotatable with respect thereto about an axis coaxial with the pipe I through which the pressurefiuid is supplied to the nozzle 4. The member'5 is rocked aboutits axis of rotationby means of V an arm and link 9, the latter being connected to the measuring instrument or other controlling member.

The nozzle I and receiving orifice 2 may have interior forms such as illustrated in Fig. 2 whilst the nozzle 4 may have an elongated mouth 4;; to

give a fan-tail type of jet; Figure 3 shows such a nozzle provided with a vane or bafile fo r controlling the main.jet. In un fig re, the small circle I 0 represents the jet normally passing from which are atan angle, for example, of with respect to one another, these jets impinging upon one another to produce a fan-tail flow which is presentededgewise to the main jet I0.

We claim:

1. A mechanical relay of the fluid jet type, comprising a pair of fluid jet nozzles arranged in substantiallyaxial' alignment and facing one anotherwhereby pressure fluid Supplied to one; 1102- zle" pmduces a fluid jet therefrom which normally tends to enter the orifice of the other'nozzle, and a thirdnozzle arranged with its axis substantially at right angles to and in proximity to said jet whereby pressure fluid suppliedto said third'noizzl'e produces a fluid jet whichimpinges upon the first-mentioned jet; said third nozzle being soinovably mounted relativly'lto said pair of nozzles as to cause its jet to' variably impinge upon the first-mentioned jet in accordance with the movements imparted; to said third nozzle and to thereby vary the amount or fluid entering said orifice of said other nozzle".

2. A re1ay as claimed in claim 1, wherein said third nozzle is movable about-arr axis'which is so disposedwith' respect to'the directiori'of efilux of the jet from one of said pair of'ii'ozzles that the latter jet produces no torque on said third nozzle about its axis of movement. I

3. A relay as claimed in claim 1, wherein said third nozzle is formed to produe'e a fan t'ail jet.

4. A relay as claimed in' claim 1; including a vane associated with said thirdiiozzle and mov- OBERT OECI ERAITHWAITE; KENNETH WILCOX. 

